Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 271018

Area Forecast Discussion
National Weather Service Bismarck ND
518 AM CDT Thu Oct 27 2016

Issued at 517 AM CDT Thu Oct 27 2016

Update for issuance of a dense fog advisory for parts of north
central ND in an near the Devils Lake Basin. Cities and towns in
the advisory include Rugby...Dunseith...Belcourt and Rolla.
Although mid level clouds were moving southeast across western
and central ND, sites like Dunseith and Rugby were reporting 1/4
mile. Will issue the advisory valid through 10 am cdt.


.SHORT TERM...(Today and tonight)
Issued at 338 AM CDT Thu Oct 27 2016

Currently...a weak surface cold front had moved south into north
central ND...allowing temperatures to drop quickly into the 30s. Low
level moisture in place with radiational cooling has increased fog
formation in the Devils Lake Basin and westward into the Minot area.
The visibilities had dropped to 1/4 mile in this area as well. The
question is whether this dense fog will persist...or begin to
dissipate because a large area of mid-level clouds was moving
east/southeast across ND. The mid level clouds covered all of
southwestern ND and into the south central. As the clouds advance
eastward, we are thinking that will raise surface temperatures just
enough to keep visibilities from being as low as 1/4 mile
(dense fog). On the other hand, the HRRR model indicates that the
area of dense fog should expand in all directions from the Devils
Lake Basin.

Expect that any low clouds or fog that develops will erode from
southwest to northeast today. A building upper level ridge and
low/mid level warming with southwest winds aloft spreading from
southwestern ND northeastward. Expect temperatures to climb into the
lower 70s southwest...but reach only into the upper 50s in the
Turtle Mountains through the James Valley.

Tonight the upper level ridge axis moves east into Minnesota and
the ridge flattens as shortwave energy impulses approach ND. The
shortwave will induce a surface low over MT Thursday afternoon.
This low is forecast to move east into central ND by daybreak
Friday. South winds ahead of the low and westerly winds behind it
should keep the overnight low temperatures quite mild in the 40s.

.LONG TERM...(Friday through Wednesday)
Issued at 338 AM CDT Thu Oct 27 2016

A cold front extending westward from the surface low over central ND
Friday daybreak is forecast to move southeast across the state as
the surface low moves east into MN. A breezy day with northwest
winds of 15 to 25 mph and highs from the mid 50s northwest to the
upper 60s south central. A secondary push of much colder air is
forecast to move into ND Friday night. Expect northwest winds to
remain at 10 to 20 mph with overnight lows in the 30s. An upper
level shortwave moving northeast across the Rockies Friday will
approach the western Dakotas Friday night and bring chances of
rain...possibly mixed with snow...mainly over southern counties
Friday night and Saturday.

The coolest day will be Saturday when the center of the cold Canadian
high reaches ND by late Saturday afternoon. Look for highs only in
the 40s.

The flow aloft remains progressive, and a vigorous shortwave moving
northeast across the Rockies will bring another chance of rain
Sunday night and Monday.

Tuesday and Wednesday look dry with seasonable temperatures with
highs in the mid 40s to mid 50s.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1237 AM CDT Thu Oct 27 2016

The forecast challenge for the 06Z TAF period is fog. KDIK and KISN
are expected to have prevailing VFR conditions, while fog is
forecast to impact KJMS...KMOT and perhaps KBIS. Dense fog was
already reported in the Devils Lake Basin including Rugby/Devils
Lake and eastward. Short term high res HRRR model indicates fog
expanding this morning to encompass along and east of the
Coteau...thus KMOT and KJMS are included. However...inhibiting the
fog is a large area of mid level clouds over southwestern ND moving
east. Thus confidence is low regarding the areal coverage and timing
of any light or dense fog at KMOT/KBIS/KJMS. Have a hint of light
fog at KMOT/KBIS but put MVFR/IFR vsbys at KJMS. Expect KJMS to
become vfr around 18z.


Dense Fog Advisory until 10 AM CDT this morning for NDZ005-013.



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